Touch screen panel

ABSTRACT

A touch screen panel provided in an image display device. The touch screen panel includes: a transparent substrate; a plurality of first sensing patterns on the transparent substrate and coupled to each other along a first direction; a first insulating film on the first sensing patterns; a plurality of second sensing patterns on the first insulating film and coupled to each other along a second direction, the first and second sensing patterns being alternately arranged not to overlap with each other; and a second insulating film on the second sensing patterns, wherein the first insulating film and the second insulating film are composed of materials having different optical refractive indexes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of Korean PatentApplication No. 10-2009-0003631, filed on Jan. 16, 2009, in the KoreanIntellectual Property Office, the entire content of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a touch screen panel provided in animage display device, etc.

2. Description of Related Art

A touch screen panel is an input device by which a user can input his orher instruction by selecting an instructed content displayed on a screensuch as an image display device, etc. using a human's finger or anobject.

To this end, the touch screen panel is provided on the front face of theimage display device to convert a contact position in direct contactwith the human's finger or object into an electrical signal. Therefore,the instructed content selected on the contact position is accepted asan input signal.

Applications of the touch screen panel are expanding widely because itcan replace an input device that is coupled to and operates the imagedisplay device such as a keyboard, a mouse, or the like.

A touch screen panel can be categorized into a resistive type, aphotosensitive type and an electrostatic capacitive type.

Among the types of touch screen panels, the electrostatic capacitivetype touch screen panel uses a conductive sensing pattern to sense achange in electrostatic capacitance formed in association with othersensing patterns in the vicinity thereof or a ground electrode, etc.,thereby converting a touch with a contact position into an electricalsignal.

Here, in order to clearly determine the contact position on the contactsurface, the sensing pattern includes first sensing patterns (Xpatterns) formed to be coupled along a first direction, and secondsensing patterns (Y patterns) formed to be coupled along a seconddirection.

The first and second sensing patterns as described above are generallypositioned in the same layer. In this case, the sensing patternspositioned on the same X or Y lines are coupled by forming separatecoupling patterns through contact holes formed on insulating films onthe upper portions thereof. Accordingly, additional masks may berequired, and the fabrication process thereof may be complicated.

In addition, the touch screen panel is positioned on the display panelsuch as a liquid crystal display panel, etc., wherein light emitted fromthe display panel reaches a user while being transmitted through thetouch screen panel. Also, an external light incident on the externalsurface of the touch screen panel is reflected. Therefore, in order todisplay a uniform image, it is desirable to prevent or reduce adifference in light reflectance from being generated from the touchscreen panel.

SUMMARY OF THE INVENTION

Aspects of the embodiments of the present invention are directed towarda touch screen panel with a reduced difference in light reflectancethroughout the entire panel, and/or toward simplifying a fabricationprocess for the touch screen panel by reducing the number of masksutilized in the fabrication process.

According to one embodiment of the present invention, there is provideda touch screen panel including: a transparent substrate; a plurality offirst sensing patterns on the transparent substrate and coupled to eachother along a first direction; a first insulating film on the firstsensing patterns; a plurality of second sensing patterns on the firstinsulating film and coupled to each other along a second directioncrossing the first direction, the first and second sensing patternsbeing alternately arranged with the first sensing patterns to notoverlap with the first sensing patterns; and a second insulating film onthe second sensing patterns, wherein the first insulating film and thesecond insulating film are composed of materials having differentoptical refractive indexes.

The first insulating layer may be composed of a material having anoptical refractive index greater than that of the second insulatingfilm.

Also, the first sensing patterns may be composed of ITO, and the firstinsulating film may be composed of a material having an opticalrefractive index between about 1.7 and about 1.8. The second sensingpatterns may be composed of a material having an optical refractiveindex between about 1.5 and about 1.65.

Also, the second insulating film may be composed of a material having anoptical refractive index between the optical refractive index of air andthe optical refractive index of the first insulating film.

Also, the first sensing patterns may be composed of ITO, and the firstinsulating film may be composed of a transparent insulating materialcomprising between about 10 and about 30 wt % of SiO2, between about 5and about 30 wt % of ZrO2, between about 1 and about 60 wt % of TiO2. Inone embodiment, the transparent insulating material of the firstinsulating film may be composed of about 30 wt % of SiO2, about 10 wt %of ZrO2, and about 60 wt % of TiO2. The second insulating film may becomposed of a transparent insulating material having a composition ofabout 20 wt % of SiO2, about 10 wt % of ZrO2, about 50 wt % of TiO2, andabout 20 wt % of SiO2 filler.

Also, the second insulating film may have a surface roughness greaterthan that of the first insulating film.

With the touch screen panel as described in the above embodiments of thepresent invention, the first sensing patterns coupled to each otheralong the first direction and the second sensing patterns coupled toeach other along the second direction are disposed on different layers,thereby making it feasible to reduce the number of masks and to simplifythe process.

Also, the optical refractive index of the first insulating layerpositioned on the first sensing patterns and the optical refractiveindex of the second insulating layer positioned on the second sensingpatterns are controlled, thereby making it feasible to improve thedifference in light reflectance that may be generated as the first andsecond sensing patterns are disposed in different layers.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, together with the specification, illustrateexemplary embodiments of the present invention, and, together with thedescription, serve to explain the principles of the present invention.

FIG. 1 is a plan schematic view showing an arrangement of sensingpatterns according to an embodiment of the present invention;

FIG. 2 is an exploded plan schematic view of a touch screen panelaccording an embodiment of the present invention;

FIG. 3 is a plan schematic view of the assembled touch screen panel ofFIG. 2;

FIG. 4 is a cross-sectional schematic view of certain parts of theassembled touch screen panel of FIG. 2; and

FIGS. 5A, 5B, 5C, 5D and 5E are cross-sectional schematic viewssequentially showing a method of fabricating the touch screen panel ofFIG. 4.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In the following detailed description, only certain exemplaryembodiments of the present invention have been shown and described,simply by way of illustration. As those skilled in the art wouldrealize, the described embodiments may be modified in various differentways, all without departing from the spirit or scope of the presentinvention. Accordingly, the drawings and description are to be regardedas illustrative in nature and not restrictive. In addition, when anelement is referred to as being “on” another element, it can be directlyon the element or be indirectly on the element with one or moreintervening elements interposed therebetween. Also, when an element isreferred to as being “connected to” another element, it can be directlyconnected to the element or be indirectly connected to the element withone or more intervening elements interposed therebetween. Hereinafter,like reference numerals refer to like elements.

Hereinafter, exemplary embodiments according to the present inventionwill be described in more detail with reference to the accompanyingdrawings.

FIG. 1 is a plan schematic view showing an arrangement of sensingpatterns according to an embodiment of the present invention.

Referring to FIG. 1, the sensing patterns according to the embodiment ofthe present invention include first and second sensing patterns 12 and14 that are alternately disposed, wherein the sensing patterns in onecolumn unit having the same X-coordinate or the sensing patterns in onerow unit having the same Y-coordinate are coupled to each other.

For example, the first sensing patterns 12 may include a plurality of Xpatterns, wherein the sensing patterns in one column having the sameX-coordinate along a first direction (a column direction) are coupled toeach other. The second sensing patterns 14 may include a plurality of Ypatterns, wherein the sensing patterns in one row having the sameY-coordinate along a second direction (a row direction) are coupled toeach other.

However, in the embodiment of FIG. 1, the first sensing patterns 12 andthe second sensing patterns 14 are disposed in different layers,respectively. For example, the first sensing patterns 12 may bepositioned in a lower layer; the second sensing patterns 14 may bepositioned in an upper layer; and insulating films may be interposedtherebetween.

As described above, if the first sensing patterns 12 and the secondsensing patterns 14 are disposed in different layers, respectively, thefirst sensing patterns 12 positioned in the same column can be formed tobe coupled to each other while patterning the first sensing patterns 12,and the second sensing patterns 14 positioned in the same row can beformed to be coupled to each other while patterning the second sensingpatterns 14.

Therefore, a process of forming separate contact holes and couplingpatterns can be omitted, thereby making it possible to reduce the numberof masks and to simplify the process.

FIG. 2 is an exploded plan schematic view of a touch screen panelaccording an embodiment of the present invention, and FIG. 3 is a planschematic view of the assembled touch screen panel of FIG. 2.

Referring to FIGS. 2 and 3, the touch screen panel 10 according to theembodiment of the present invention includes a transparent substrate 11.In addition, the touch screen panel 10 includes first sensing patterns12, a first insulating film 13, second sensing patterns 14, metalpatterns 15 and a second insulating film 16 that are formed sequentiallyon the transparent substrate 11.

The first sensing patterns 12 are formed on one surface of thetransparent substrate 11 to be coupled to each other along a firstdirection. For example, the first sensing patterns 12 may be formed onthe upper surface of the transparent substrate 11 to be closed to eachother, having a regular pattern such as a diamond pattern. The firstsensing patterns 12 as described above may include a plurality of Xpatterns, wherein the first sensing patterns 12 in one column having thesame X-coordinate are coupled to each other. Here, the shapes of thefirst sensing patterns 12 are not limited to the diamond shape patterns,but it may be implemented as various suitable shapes such that thesensing patterns can be close to each other.

The first sensing patterns 12 have pads 12 a that are electricallycoupled to the metal patterns 15 for each column of the first sensingpatterns 12. The pads 12 a of the first sensing patterns 12 may bealternately provided on the upper side or the lower side, may bepositioned on the upper side or the lower side, or may be positioned onboth the upper and lower sides, for each column of the first sensingpatterns 12.

However, the first sensing patterns 12 are formed not to be overlappedwith the second sensing patterns 14, except for the coupling portionsthereof. In other words, the first sensing patterns 12 and the secondsensing patterns 14 are disposed alternately to cross each other.

The first insulating film 13 is formed on the first sensing patterns 12to cover them.

The second sensing patterns 14 are formed on the first insulating layer13 to be coupled to each other along a second direction, but aredisposed alternately with the first sensing patterns 12 so as not to beoverlapped with the first sensing patterns 12. For example, the secondsensing patterns 14 may be formed to be closed to each other, having thesame diamond pattern as the first sensing patterns 12, and may include aplurality of Y patterns, wherein the second sensing patterns 14 in onerow having the same Y-coordinate are coupled to each other.

The second sensing patterns 14 have pads 14 a that are electricallycoupled to the metal patterns 15 for each row of the second sensingpatterns 14. The pads 14 a of the second sensing patterns 14 may bealternately provided on the left side or the right side, may bepositioned on any one of the left side or the right side, or may bepositioned on both the left and right sides, for each row of the secondsensing patterns 14.

In addition, the first and second sensing patterns 12 and 14 and thefirst insulating film 13 are composed of a transparent material so thatlight emitted from a display panel, etc. disposed below the lowerportion of the touch screen panel 10 can transmit through the touchscreen panel 10. In one embodiment, the first and second sensingpatterns 12 and 14 are composed of a transparent electrode material suchas indium tin oxide (hereinafter, referred to as ITO), and the firstinsulating film 13 is composed of a transparent insulating material.Here, the term of transparent refers to a high light transmittance aswell as being transparent by 100%.

The thicknesses of the first and second sending patterns 12 and 14 andthe first insulating film 13 can be set to be within a suitable rangesuch that the touch screen panel 10 (in particular, the first and secondsensing patterns 12 and 14) have a relatively low surface resistance,and can provide sufficient transmittance of light transmitted from thedisplay panel. In other words, the thickness of the first and secondsensing patterns 12 and 14 and the first insulating film 13 can bedesigned in consideration of the transmittance and the surfaceresistance.

In one embodiment, each of the first and second sensing patterns 12 and14 may be formed of an indium tin oxide (ITO) pattern having a thicknessbetween 100 and 300 Å, and the first insulating film 13 may be composedof a transparent insulating material having a thickness between 400 and1000 Å (e.g., a thickness between 400 and 700 Å). However, this ismerely one embodiment, and the present invention is not limited thereto.Therefore, the thickness thereof may also be suitably changed inconsideration of the desired transmittance and/or the surfaceresistance, etc.

The metal patterns 15 are disposed on the edge portions of the regionswhere the first and second sensing patterns 12 and 14 are formed, forexample, on regions corresponding to the pads 12 a and 14 a of the firstand second sensing patterns 12 and 14. The metal patterns 15 asdescribed above are electrically coupled to the sensing patterns 12 and14 in row units and/or in column units to position detecting lines,respectively, to allow contact position detecting signals to be suppliedto a driving circuit, etc.

The second insulating film 16 is formed on the second sensing patterns14 to cover them. In one embodiment, the second insulating film 16 maybe formed on the second sensing patterns 14, composed of a transparentinsulating material having a thickness between 400 and 1000 Å.

If the assembled touch screen panel 10 as shown in FIG. 3 is touched bya human's hand or an object, a change in electrostatic capacitance inaccordance with the contact position is transferred to the drivingcircuit via the first and second sensing patterns 12 and 14, the metalpatterns 15 and the position detecting lines. The change inelectrostatic capacitance is converted into an electrical signal, forexample, by the X and Y input processing circuits, etc. so that thecontact position is determined.

With the touch screen panel 10 as described in the above embodiments,the first sensing patterns 12 coupled to each other along the firstdirection and the second sensing patterns 14 coupled to each other alongthe second direction are disposed in different layers, thereby making itfeasible to reduce the number of masks used in the fabrication processof the touch screen panel 10 and to simplify the process.

FIG. 4 is a cross-sectional schematic view of certain parts of theassembled touch screen panel of FIG. 2. When describing FIG. 4, the samereference numerals are given to the same elements as shown in FIGS. 2and 3, and the detailed description thereof will be omitted.

Referring to FIG. 4, the first sensing patterns 12 and the secondsensing patterns 14 are interposed between the first insulating film 13and are disposed alternately on different layers.

If the first and second sensing patterns 12 and 14 are disposed ondifferent layers as described above, the first or second sensingpatterns 12 or 14 positioned in the same row and in the same column canbe coupled during a patterning step. Therefore, a process of formingcontact holes for coupling the first or second sensing patterns 12 or 14positioned in the same row and/or in the same column may be omitted.

In addition, a transparent ground electrode 17 and a third insulatingfilm 18 that covers the transparent ground electrode 17 may be furtherformed on the other surface opposite to the surface of the transparentsubstrate 11 on which the first and second sensing patterns 12 and 14are formed, that is, on the lower surface of the transparent substrate11.

In one embodiment, the transparent ground electrode 17 composed of atransparent electrode material such as ITO, etc. having a thicknessbetween 100 and 300 Å may be formed on the lower surface of thetransparent substrate 11, and the third insulating film 18 that coversthe transparent ground electrode 17, having a thickness between 400 and1000 Å, may be formed on the lower surface of the transparent groundelectrode 17.

However, the above described embodiment is merely one embodiment, andthe thickness of the transparent ground electrode 17 and the thirdinsulating film 18 may be suitably modified in consideration of thedesired light transmittance, etc. Also, the transparent ground electrode17 and/or the third insulating film 18 may also be omitted according tothe design of a product.

The transparent ground electrode 17 may be utilized in securingstability between the touch screen panel 10 and the display panel, etc.Also, the transparent ground electrode 17 may be used together with thefirst and second sensing patterns 12 and 14 to form the electrostaticcapacitance according to the design method of the touch screen panel 10.

For example, in the electrostatic capacitive type touch screen panel 10,in order to sense the contact position, the electrostatic capacitancebetween the first sensing pattern 12 and the second sensing pattern 14may be utilized, or the electrostatic capacitance between the first andsecond sensing patterns 12 and 14 and the transparent ground electrode17 may be utilized, wherein these sensing patterns may be suitablymodified.

However, in some embodiments of the present invention, the firstinsulating film 13 and the second insulating film 16 are composed ofmaterials having different optical refractive indexes.

In one embodiment, the first insulating film 13 is composed of amaterial having an optical refractive index that is similar to anoptical refractive index of the first sensing patterns 12, and thesecond insulating film 16 is composed of a material having an opticalrefractive index that is smaller than the optical refractive index ofthe first insulating film 13.

For example, when the first sensing patterns 12 are composed of ITO, thefirst insulating film 13 may be composed of a material having an opticalrefractive index of between 1.7 and 1.8 (based on 550 nm wavelength).The second insulating film 16 may be composed of a material having anoptical refractive index between the optical refractive index of air andthe optical refractive index of the first insulating film 13, forexample, an optical refractive index of between 1.5 and 1.65.

As described in the above embodiment, when the first and secondinsulating films 13 and 16 are formed in a multi-layer structure, thefirst insulating film 13 in the lower portion that is closer to thedisplay panel is composed of a material having an optical refractiveindex between the optical refractive index of the transparent substrate11 and the optical refractive index of the first sensing patterns 12,and the second insulating film 16 in the upper portion is composed of amaterial having an optical refractive index between the opticalrefractive index of air and the optical refractive index of the firstinsulating film 13.

Accordingly, the difference in light reflectance in the touch screenpanel 10 that may occur as the first and second sensing patterns 12 and14 are disposed on different layers can be improved as well as improvingoptical efficiency by reducing reflective light.

In addition, the first insulating film 13 is formed to have a suitablysmall heat deformation and a reduced surface roughness. Therefore thechange in surface resistance of the first sensing patterns 12 isminimized or reduced, and the film formation of the second sensingpatterns 14 is firmed.

By way of one example, in order to have the optical refractive indexsatisfying the conditions as described above, the first insulating film13 may be composed of a transparent insulating material containingbetween 10 and 30 wt % of silicon dioxide (hereinafter, referred to asSiO2), between 5 and 30 wt % of zirconium oxide (hereinafter, referredto as ZrO2), and between 1 and 60 wt % of titanium dioxide (hereinafter,referred to as TiO2).

In one embodiment, the first insulating film 13 with a suitable opticalrefractive index may be implemented by utilizing a transparentinsulating material having a composition including 30 wt % of SiO2, 10wt % of ZrO2, and 60 wt % of TiO2.

Also, the second insulating film 16, which is an external layer comparedto the first insulating film 13, may have its durability suitablyreinforced against impact or scratch, etc. and have a surface roughnessgreater than the first insulating film 13. To this end, the compositionof the second insulating film 16 may be suitably controlled by adding,for example, SiO2 granules, etc.

The second insulating film 16 as described above with a suitable opticalrefractive index may be implemented by utilizing a transparentinsulating material having the composition including 20 wt % of SiO2, 10wt % of ZrO2, 50 wt % of TiO2, and 20 wt % of SiO2 filler.

In other words, in the above described embodiments of the presentinvention, the optical efficiency is enhanced through the matching ofthe optical refractive index between the first insulating film 13 andthe second insulating film 16, such that the difference in lightreflectance of the entire touch screen panel 10 can be improved.

FIGS. 5A to 5E are cross-sectional schematic views sequentially showinga fabrication method of the touch screen panel of FIG. 4.

First, referring to FIG. 5A, a transparent electrode material such asITO is deposited on an upper portion of a transparent substrate 11 andthen is patterned, thereby forming first sensing patterns 12. Here,although coupling parts of the first sensing patterns 12 are not shown,the first sensing patterns 12 are patterned in order to be coupled toeach other in a first direction (for example, in a column direction).

Thereafter, as shown in FIG. 5B, a first insulating material is printedand fired (or cured) on the first sensing patterns 12 by utilizing asuitable printing method that is relatively simple, thereby forming afirst insulating film 13. In addition, the feature that the firstinsulating film 13 is formed by utilizing the printing method is merelyone embodiment of the present invention, and the present invention isnot limited thereto. For example, the first insulating film 13 may beformed by using a chemical vapor deposition (CVD) method and/or asputtering method.

Thereafter, as shown in FIG. 5C, a transparent electrode material suchas ITO is deposited on the first insulating film 13 and then ispatterned, thereby forming the second sensing patterns 14. Here, thesecond sensing patterns 14 are disposed not to be overlapped with thefirst sensing patterns 12 (however, the coupling parts of the secondsensing patterns 14 may be excluded). The second sensing patterns 14 arepatterned in order to be coupled to each other in a second direction(for example, in a row direction).

In addition, after the second sensing patterns 14 are formed, the metalpatterns 15 and position detecting lines, etc. shown in FIGS. 2 and 3are further formed by utilizing a low resistance material having lowersurface resistance than the transparent electrode material, such as atriple-layer of molybdenum/aluminum/molybdenum or a chrome film, etc.

Thereafter, as shown in FIG. 5D, a second insulating material is printedand fired (or cured) on the second sensing patterns 14 and the metalpatterns 15 in FIGS. 2 to 3 by utilizing a printing method, therebyforming a second insulating film 16. In addition, the method of formingthe second insulating film 16 is not limited only to the printingmethod, but the second insulating film 16 may be formed by utilizing aCVD method and/or a sputtering method. In one embodiment, in order toreinforce the surface hardness of the second insulating film 16, thesecond insulating film 16 may be formed by utilizing the CVD method.

Thereafter, as shown in FIG. 5E, a transparent ground electrode 17 isdeposited over the bottom surface of the transparent substrate 11 andfurthermore, a third insulating film 18 is formed by utilizing theprinting method, the CVD method and/or the sputtering method, etc., inorder to cover the transparent ground electrode 17.

If the touch screen panel as described in the embodiments of the presentinvention is fabricated as described above, the mask process isminimized, and the process step is simplified, thereby making itpossible to enhance process efficiency.

While the present invention has been described in connection withcertain exemplary embodiments, it is to be understood that the inventionis not limited to the disclosed embodiments, but, on the contrary, isintended to cover various modifications and equivalent arrangementsincluded within the spirit and scope of the appended claims, andequivalents thereof.

1. A touch screen panel comprising: a transparent substrate; a pluralityof first sensing patterns on the transparent substrate and coupled toeach other along a first direction; a first insulating film on the firstsensing patterns; a plurality of second sensing patterns on the firstinsulating film and coupled to each other along a second directioncrossing the first direction, the second sensing patterns beingalternately arranged with the first sensing patterns to not overlap withthe first sensing patterns; and a second insulating film on the secondsensing patterns, wherein the first insulating film and the secondinsulating film are composed of materials having different opticalrefractive indexes, and wherein the first insulating film is composed ofa material having an optical refractive index greater than that of thesecond insulating film.
 2. The touch screen panel as claimed in claim 1,wherein the first sensing patterns are composed of ITO, and the firstinsulating film is composed of a material having an optical refractiveindex between about 1.7 and about 1.8.
 3. The touch screen panel asclaimed in claim 2, wherein the second sensing patterns are composed ofa material having an optical refractive index between about 1.5 andabout 1.65.
 4. The touch screen panel as claimed in claim 1, wherein thesecond insulating film is composed of a material having an opticalrefractive index between the optical refractive index of air and theoptical refractive index of the first insulating film.
 5. The touchscreen panel as claimed in claim 1, wherein the first sensing patternsare composed of ITO, and the first insulating film is composed of atransparent insulating material comprising between about 10 and about 30wt % of SiO2, between about 5 and about 30 wt % of ZrO2, between about 1and about 60 wt % of TiO2.
 6. The touch screen panel as claimed in claim5, wherein the transparent insulating material of the first insulatingfilm is composed of about 30 wt % of SiO2, about 10 of wt % ZrO2, andabout 60 wt % of TiO2.
 7. The touch screen panel as claimed in claim 6,wherein the second insulating film is composed of a transparentinsulating material having a composition of about 20 wt % of SiO2, about10 wt % of ZrO2, about 50 wt % of TiO2, and about 20 wt % of SiO2filler.
 8. The touch screen panel as claimed in claim 1, wherein thesecond insulating film has a surface roughness greater than that of thefirst insulating film.